Dielectric additive enables humidity-independent preparation of blend morphology for high-performance, large-area organic photovoltaics

Dielectric material in bulk-heterojunctions can play critical roles in exciton polarization and morphology control. We develop carvone (CV) dielectric additive to prepare high-efficiency, large-area organic photovoltaics (OPVs). CV forms a complex with L8-BO, which enhances forming uniform crystallites of acceptors as well as exciton dissociation in D18:N3:L8-BO blend. Furthermore, strong inward Marangoni flows induced by CV addition during blade coating enable the evolution of homogeneous morphology over large areas, irrespective of the surface energy of the electron-transporting layer. As a result, OPVs exhibited improved performances and, in particular, the device using binary D18:PM6 donors achieved efficiency of 17.44% for an active area of 1 cm² and the corresponding module showed 16.27% efficiency. This is among the highest OPV module efficiency achieved, with active areas above 20 cm². Importantly, it is demonstrated that CV addition is effective for reproducible preparation of the optimal blend morphology in ambient air with relative humidity from 10% to 70%.